package com.glinsoft.waterbatis.ext;

import java.io.IOException;
import java.lang.annotation.Annotation;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.core.type.filter.AssignableTypeFilter;
import org.springframework.core.type.filter.TypeFilter;
import org.springframework.util.ClassUtils;

/**
 * class扫描
 */
public class ClassScanner {

    private static final String RESOURCE_PATTERN = "/**/*.class";

    private ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();

    private List<String> packagesList = new LinkedList<String>();

    private List<TypeFilter> typeIncludes = new LinkedList<TypeFilter>();

    private Set<Class<?>> classSet = new HashSet<Class<?>>();

    @SuppressWarnings("unchecked")
    public ClassScanner(String[] entityPackage, Class<?> scanClass) {
        for (String packagePath : entityPackage) {
            this.packagesList.add(packagePath);
        }
        // scanClass是注解类型
        if (scanClass.isAnnotation()) {
            // AnnotationTypeFilter 有scanClass注解的类将被过滤出来,不能过滤接口
            typeIncludes.add(new AnnotationTypeFilter((Class<? extends Annotation>) scanClass, false));
        } else {
            // AssignableTypeFilter 继承或实现superClass的类将被过滤出来
            // superClass可以是接口
            typeIncludes.add(new AssignableTypeFilter(scanClass));
        }

    }


    /**
     * 将符合条件的Bean以Class集合的形式返回
     *
     * @return 返回Mapper的class集合
     * @throws IOException            IO异常
     * @throws ClassNotFoundException 文件找不到异常
     */
    public Set<Class<?>> getClassSet() throws IOException, ClassNotFoundException {
        this.classSet.clear();
        if (!this.packagesList.isEmpty()) {
            for (String pkg : this.packagesList) {
                // classpath*:com/xx/dao/**/*.class
                String pattern = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
                        + ClassUtils.convertClassNameToResourcePath(pkg) + RESOURCE_PATTERN;
                Resource[] resources = this.resourcePatternResolver.getResources(pattern);
                MetadataReaderFactory readerFactory = new CachingMetadataReaderFactory(this.resourcePatternResolver);
                for (Resource resource : resources) {
                    if (resource.isReadable()) {
                        MetadataReader reader = readerFactory.getMetadataReader(resource);
                        if (matchesEntityTypeFilter(reader, readerFactory)) {
                            String className = reader.getClassMetadata().getClassName();
                            this.classSet.add(Class.forName(className));
                        }
                    }
                }
            }
        }
        return this.classSet;
    }

    /**
     * 检查当前扫描到的Bean含有任何一个指定的注解标记
     *
     * @param reader
     * @param readerFactory
     * @return 返回true表示它是一个Mapper
     * @throws IOException
     */
    private boolean matchesEntityTypeFilter(MetadataReader reader, MetadataReaderFactory readerFactory)
            throws IOException {
        if (!this.typeIncludes.isEmpty()) {
            for (TypeFilter filter : this.typeIncludes) {
                if (filter.match(reader, readerFactory)) {
                    return true;
                }
            }
        }
        return false;
    }
}
